I think for such a scenario you'd need read locks which gets upgraded to write locks when modifying. Consider this simple scenario w/o read locks:
Thread ONE: get relationship R Thread TWO: get relationship R Thread TWO: delete relationship R and commit transaction Thread ONE: do any modification on relationship R... BOOM Exception If read locks were to be taken when getting relationships: Thread ONE: get relationship R Thread TWO: get relationship R Thread TWO: would like to delete relationship R, but will have to wait until Thread ONE releases its read lock on it Thread ONE: do some modification on relationship R and commit transaction Thread TWO: lock from Thread ONE was released so delete relationship R and commit transaction Unfortunately you cannot provide different isolation levels in neo4j at the moment, but you could mimic that behavior yourself using LockManager/LockReleaser (from graphDb.getConfig()) 2011/11/21 Aseem Kishore <aseem.kish...@gmail.com> > Hey guys, > > If we put our app under a bit of load, creating and removing nodes and > relationships concurrently, sometimes we get back a 500 Internal Server > Error from the REST API when we do a traverse or Cypher query. Here's an > example stack trace: > > https://gist.github.com/1381423 > > We're running Neo4j. 1.4 still, but does this stack trace provide any > insight/ideas into what might be wrong, what we could do as a workaround, > etc.? Can I provide any other info that would help? > > It goes without saying that our assumption is that Neo4j shouldn't be > failing/crashing on queries; our expectation was that operations are > transactional, etc. > > Thanks! > > Aseem > _______________________________________________ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > -- Mattias Persson, [matt...@neotechnology.com] Hacker, Neo Technology www.neotechnology.com _______________________________________________ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
